[PATCH bpf-next v3 01/12] bpf: sockmap: only check ULP for TCP sockets

Lorenz Bauer
2020-03-04T10:14:35Z

The sock map code checks that a socket does not have an active upper
layer protocol before inserting it into the map. This requires casting
via inet_csk, which isn't valid for UDP sockets.

Guard checks for ULP by checking inet_sk(sk)->is_icsk first.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
---
include/linux/skmsg.h | 8 +++++++-
include/net/inet_connection_sock.h | 6 ++++++
net/core/sock_map.c | 6 ++----
net/ipv4/tcp_ulp.c | 7 -------
4 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index 112765bd146d..4d3d75d63066 100644
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -360,7 +360,13 @@ static inline void sk_psock_restore_proto(struct sock *sk,
struct sk_psock *psock)
{
sk->sk_prot->unhash = psock->saved_unhash;
- tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
+ if (inet_csk_has_ulp(sk)) {
+ tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
+ } else {
+ sk->sk_write_space = psock->saved_write_space;
+ /* Pairs with lockless read in sk_clone_lock() */
+ WRITE_ONCE(sk->sk_prot, psock->sk_proto);
+ }
}

static inline void sk_psock_set_state(struct sk_psock *psock,
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 895546058a20..a3f076befa4f 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -335,4 +335,10 @@ static inline void inet_csk_inc_pingpong_cnt(struct sock *sk)
if (icsk->icsk_ack.pingpong < U8_MAX)
icsk->icsk_ack.pingpong++;
}
+
+static inline bool inet_csk_has_ulp(struct sock *sk)
+{
+ return inet_sk(sk)->is_icsk && !!inet_csk(sk)->icsk_ulp_ops;
+}
+
#endif /* _INET_CONNECTION_SOCK_H */
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 2e0f465295c3..cb8f740f7949 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -384,7 +384,6 @@ static int sock_map_update_common(struct bpf_map *map, u32 idx,
struct sock *sk, u64 flags)
{
struct bpf_stab *stab = container_of(map, struct bpf_stab, map);
- struct inet_connection_sock *icsk = inet_csk(sk);
struct sk_psock_link *link;
struct sk_psock *psock;
struct sock *osk;
@@ -395,7 +394,7 @@ static int sock_map_update_common(struct bpf_map *map, u32 idx,
return -EINVAL;
if (unlikely(idx >= map->max_entries))
return -E2BIG;
- if (unlikely(rcu_access_pointer(icsk->icsk_ulp_data)))
+ if (inet_csk_has_ulp(sk))
return -EINVAL;

link = sk_psock_init_link();
@@ -738,7 +737,6 @@ static int sock_hash_update_common(struct bpf_map *map, void *key,
struct sock *sk, u64 flags)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
- struct inet_connection_sock *icsk = inet_csk(sk);
u32 key_size = map->key_size, hash;
struct bpf_htab_elem *elem, *elem_new;
struct bpf_htab_bucket *bucket;
@@ -749,7 +747,7 @@ static int sock_hash_update_common(struct bpf_map *map, void *key,
WARN_ON_ONCE(!rcu_read_lock_held());
if (unlikely(flags > BPF_EXIST))
return -EINVAL;
- if (unlikely(icsk->icsk_ulp_data))
+ if (inet_csk_has_ulp(sk))
return -EINVAL;

link = sk_psock_init_link();
diff --git a/net/ipv4/tcp_ulp.c b/net/ipv4/tcp_ulp.c
index 2703f24c5d1a..7c27aa629af1 100644
--- a/net/ipv4/tcp_ulp.c
+++ b/net/ipv4/tcp_ulp.c
@@ -105,13 +105,6 @@ void tcp_update_ulp(struct sock *sk, struct proto *proto,
{
struct inet_connection_sock *icsk = inet_csk(sk);

- if (!icsk->icsk_ulp_ops) {
- sk->sk_write_space = write_space;
- /* Pairs with lockless read in sk_clone_lock() */
- WRITE_ONCE(sk->sk_prot, proto);
- return;
- }
-
if (icsk->icsk_ulp_ops->update)
icsk->icsk_ulp_ops->update(sk, proto, write_space);
}
--
2.20.1